Desiccated milk and process of making the same.



W. H. SWENARTON. DESIGGATED MILK AN PROCESS OF MAKING THE SAME.

' APPLICATION FI LED JUNE 12, 1911.

1,056,719, Patented Mar; 18, 1913.

Inventor:

' wa rrsrrnil n, 'swENA n'roN, 'or Monro-Lain, NEW JERSEY.

'- nnsrcoarnnltinx AND rnocsss or MAKING THE sum.

original application me airan ar' 21a 1906, semi in. 295,886. Divided andthis application filed June i To aZl whom it may concerni" the Process 'AR'roN, a citizen-of'the United States, resid-'; in'g in'M'ontclair, county of Essex, and State. of New Jersey, have invented newand use-; .ful- Improvements in' Desiccated Milk andofMaking theSame, of which;

the following isafispecification. a

My invention relates to the desiccation of milk and has for its object the production of themilk-s'olids in the form of a flutfyf' flaky powder, whichupon the addition of;

warm water thereto-will readily dissolve and emulsify to form a liquidhaving all the propert-ies of normal milk. These objects I attain; -by;delivering a -film of homogeneously con-, eentrated milk, free from unconcentrated.

portions, to moving heated surfaces initiallyheated in excess of five (5) degrees cent1-Q- grade above'the'boilingpoint of the milk atthe pressures at which the operation is'. performed, The film is cooled during the formation ofthesame by the'inflowing milk in its passage to'the receiving receptacle but without. direct contact therewith and is re-I moved fromthe heating surface prior tothe complete evaporationof the water there-';

moist appearance.

Milk has long'been considered a typical emulsion, andmaturally the casein, which is from and while still possessing a slightly;

-,the'principal proteid constituent, exists in' the form of whathas been termed a dicalcium caseinate, which, owing to its aflinity. .for water, is in a highly swollen state; If the so-called poise of the'calcium caseinate -molecule is affected, either by protracted heating at those temperatures at which the calcium salts precipitate, or by excessive drying, the calcium caseinate loses to a greater or less extent this aflinity for water and thereforethe formationof a. perfect, emulsion upon the addition of warm water, tothe dry product,-.no longer results,

Besides casein, milk and especially skimmilk, contains. in almost equal amounts;

' lactose orlmilkssugar. This mllk-suga'r norf Jnally c stall-izes with-one molecule of wateralls 51 209 A h this W t is; not yielded up after crystallization hajsi taken; pla e.

milk-sugar is dissolved, may {be entirely evaporated at temperatures much -.l-bel'ow condition.

until the temperature reaches a j u -.1 0 .9; me e l i t i t ra ch? crystallization the water present in whichfthe v 1 12,1911. Serial No. 632,640.

the boiling point of water at the pressure at 140 C., andthese temperatures ap i a Be it knmfill thattI, WA'ITSTILL H. SwEN- which the process is performed. Then again milk-sugar caramelizes when heated in the air to high temperatures and in a concentrated air has an energetic action upon the same and renders it very diflicultly soluble. The .Well known skinv which forms when milk is heated in theair for protracted periods even at the boiling point illustrates the. above noted changes in the casein and milk sugar due to protracted heating in the air. The

ing processes.

At high temperatures also the proper treatment of the two ingredients above noted, therefore, is thecrux of all dryto which method of drying my processpan ticularly relates,. temperatures used have I been such that the heating surface or roll was maintained at and' even in rare instances above the boiling point of the liquid in the vacuum maintained, but in each instance, either the temperature of the medium used to-heatthe surface or roll, which temperature is approximately indicated by the initial temperature of the roll, was less than five (5) degrees centigrade above the 1 boiling point of the particular vacuum maintained, or again in cases Where the temperature was sufficiently high, the method of delivering the milk to the heating surface was such that an unequal and non-homogeneous layer was deposited upon said rolls.

In the former process, owing to the considerable cooling effect of the large body ofin flowing unconcentrated liquid in the net-aining-pocket or receptacle, the temperature of the heating surface falls to such an extent water in the film (as distinguished from immediate boiling), fails to occur and hence .in'lieu of a ten second period of heating of thefilm as is the case in my process asv hereinafter described, in many cases forty- 4 five seconds is required, with the results due concentrated liquid naturally required less .fito prolonged heating heretofore noted; In" the latter process since a thin layer of unthat. the immediate vaporization of themade for the five per cent. of water which the molecule of milk sugar is capable of chemically uniting with, but the milk was reduced to complete or bone dryness as is borne out by the reference in those cases to subsequent grinding in a pebble mill or otherwise in order to produce an impalp'able powder which could thus offer the largest possible surface to any liquid added thereto.

These products, however, notwithstanding their impalpable condition, were granular of from 65 C. to 70 C. are maintained for periods extending over several minutes, a momentary heating period requires a higher temperature for the destruction of the bacteria and in both cases a temperature in those skilled in the art to" practise the same,

excess of 75 C. is req ired to destroy the spores which in certain instances even multiply at 70- C. Owing to the violent agitation and thorough heating of every particle of the milk, even momentary heating above 70 C.-'serves in my process to destroy substantially all deleterious bacteria.

Having thus indicated the nature and ob-' ject of my process, and in order to enable I will now proceed to describe my preferred mode of performing it, reference being had to the apparatus disclosed in the accompanying drawings, forming a part of this specification.

In both the specification and claims I iiiclude' under the term milk various lacteal liquids having similar properties, such as normal milk, skim-milk, modified milk, solutions of casein, etc.

The process may be carried out in any suitable apparatus, such for example. as described in my copending application, No.

1 295886 filed January 13, 1906, of which this is a division, (matured into Patent 995,303,

chiefly in' section, of a single evaporating cylinder as'employed either in .a vacuum v c dated June13,'*1911), ,onemodification of which is shown, for the purpose of illustration, in the accompanying drawings in which the 'figure shown is. in elevation,

amber 01min the open air.

Referring to the drawings, the numeral 1- Y represents the supply pipe which is in com- 6o I v "ffo'rc'ed' feed,iif desired. A distributer Q is extended at the bottom 3 in the form of an .municationlwithi a reservoir (not shown) and may be arranged .m ermir of gravity feed of the milk in lieu ofthe customary I are whichumay, if desired, possess a radius f equal to that of theabuttin'g cylinder and y v Ils. preferably-ofnickelsteel. The supply 'iiiln wfi'ile -forming to infiowing milk in its .pipe 1 is connected with. the arc-like extension distant from the cylinder and adjustable conical valves 4, on stems 5 (partially shown), serve to regulate the supply of milk to the retaining pocket 6 formed between 'the distributer and the abutting cylinder 7.

A doctor 8 serves to remove the tenacious film from the cylinder when the same is revolving in the direction indicated by the arrow.

The operation of my process, as preferably carried out is as follows: The milk is delivered to the retaining pocket formed by the abutting distributer and cylinder and the temperature of the cylinder ispreferably of the boiling point if a temperature suflicient to destroy the developed bacteria ard not the spores is used, as for example 75 C., then a vacuum of 54.5 cm.

is preferably maintained. If it be desired to produce a so-called milk-powder capable of reproducing a solution in which lactic acid fermentation progresses on standing, in a manner similar to that in the case of normal milk, and which solution will be readily peptonized by rennet, I preferably heat the cylinder to 54.5" C. while maintaining a vacuum corresponding to 459' C. or as given in physico-chemical tables 68.6 cm.

-' In order to eliminate the well known skin fromed by the action of air at high temperatures upon the casein, milk-sugar and various salts normally found in milk, and which skin caused the occlusion of the steam with a consequential protracted heating of the milk' solids, whether evaporating under low vacuum or in the open air, I have discovered an economical and effective method whereby the film while forming, is maintained below the temperature at which the said deleterious action occurs, or as it may be termed, the critical temperature, and the heat so abstracted is conserved and utilized to heat the inflowing milk in its passage to the retaining pockets. This cooling eifectI accomplish by causing the milk in its passage from the reservoir to the distributer, to expandinto a thin layer or sheet, and to contact with the opposite surface of the nipping or film-forming wall from that in contact'with the concentrated milk in the retaining pocket and adjacent the area Where the formation of said film occurs. The bottom of the distributer, as shown, is extended in the form of an are, which preferably is from 1.5 to 2.5 cm. across at a point adjacent the forming film The bottom of saiddistributer may be either extended along the entire length, or it. maybe extended at intervals along the same, without departing from the spiri't of my invention which includes any in'ethodfiof transference'of-the heat from the .cylinder whereby a continuous sheet of milk I of the above depth may be caused to cool the I I claim and 5 circulation of milk along the same is entirely i unimpeded. In practice my distributer is provided with extremely thin walls in order to effect the greatest amount of coo-ling of the film and suitable adjusting means are provided, whereby the distance of the distributer from the cylinder may be accurately,

regulated.

Whichever one of the above methods of delivering the milk is selected is immaterial in so far'as the next stage of the process is concerned, as the water in the milk,-upon cont-act with the highly heated cylinders (highly heated with respect to the vacuum) is immediately vaporized and unless the film is almost instantly removed therefrom while still slightly moist and tenacious, the water of crystallization, which serves as a margin of safety so to speak, is evaporated with the resultant destruction of the desired properties heretofore noted. In practice the film is removed while still vpossessing a slightly moist appearance arid-"while retaining suiticientwater to possess when cool a moisture content in excess of 1% and in the case of milk consisting of whole milk and skim milk the powder should contain from 2% to 4% of moisture. On cooling a film containing the amount of moisture stated, the

' chemical and physical absorption of water as occurs with the production of a perfectly dry powder, which owing to the entire absence 'of caking while evaporating, readily disinte ates and may be sifted to a light, flufiy, aky powder approximating S. G. without resorting to grinding as is customary in other-vacuum processes.

A speed of six revolutions per minute as against one revolution in 45 seconds customary in another well known vacuum process, can be maintained in my process and in practice the size of the rolls is such that this peripheral speed of speed isequivalent' to a 14 meters penminute. I The term palpable as used in the claims pable product which is inevitably deposited in the well-known atomization processes for drying milk-like products,'andany products produced by such processes, or by other processes carried-out at normalor supernormal atmospheric cally disclaimed.

Having thus described my invention,what

1. The process of desiccatingthe solid- J concentrating abody of milk in vacuo, withdrawing a thin layer of milk therefrom, de-] 86 ,livering said thin layer of milk onto an is employed to distinguish from the impal-.

pressures are hereby specifi desire to secure by Letters Pat content of milk which consists in rapidlyevaporating surface in var-11o, heated in sufficient excess of the boiling point of the vacuum to effect rapid evaporation of the liquid content of said milk below seventyfive (75) degreescentigrade, and then removing the film from such surface in such a condition that its moisture content when cool is in excess of one and one-half per cent.

' 2. The process of desiccating the solidcontent of milk which consists in rapidly concentrating a body of milk in wwuo, withdrawing a thin layer of milk therefrom, delivering said thin layer of milk onto an evaporating surface in 'vacuo, heated in sufficient excess of the boiling point of the "acuum to effect rapid evaporation of the liquid content of said milk'below seventyfive degrees centrigrade, and then removing the film from such surface in such a condition that its moisture content when cool is in excess of between one and one-half and five and one-half percent.

3. The process of desiccating the Solid Y.

content of milk which consists in rapidly concentrating a body of milk in vac-1w, withdrawin a thin layer of milk therefrom,

while efiecting a transfer of heat units from the outer surface of said film to the inflowing milk in close proximity thereto and out of contact therewith.

4. In theprocessof desiccating the solidcontent of milk in cacao by contact with a moving surface heated in excess of five degrees centigrade above the boilingpoint of the vacuum, the steps which consist in conveying a mass of milk from the source of supply While under pressure of at least atmospheric, through a covered conduit into content; then maintaining a vacuum immediately above the relatively large, exposed surface of the milk in said receptacle, while maintaining same out of direct contact with a moving evaporating surface heated in excess of five degrees centigrade above the boiling point of the vacuum whereby expansion of said ,milk prior to contact with said surface is permitted, and then delivering said milk onto said moving" surface while the latter is-heated in excessof five degrees centigrade above the boilingpoint of the milk in said vacuum, and below seventyfive de rees cent-igrade, and then removing said mllk in the form of a self-sustaining mass having the identity of a film from said surface in such a condition that its moisture- :content when dry and cool. is in excess of one and one-half per cent. a y

5. The rocess of desiccating the solidcont'ent 0 milk which consists in rapidly concentrating a body of milk'z'n cacao, with drawing a thin layer of milk therefrom, delivering said thin layer of milk onto an evaporating surface in casua heated in suflicient excess of the boiling point of the vacua receptacle of relatively large superficial um to effect rapid evaporation of the liquid content ofsaid milk below sixty degrees centigrade, and then removing the film from such Surface in suoha condition that its moisture content when cool is in excess of one and one-half per cent.

6. The process of desiccating the solid-- content of milk which consists in rapidly concentrating a body of milk in tomato, withdrawing a thin layer of milk therefrom,

delivering said thin layer of milk onto an evaporating surface in cacao, heated in sufiicient excess of the boiling point of the vacuum toefi'ect rapid evaporation of the liquid content of said milk below fifty-five de ees such surface in such a condition that its moisture contentwhen cool is in excess of one and one-half per cent.

7 The product resulting from the desiccation of the solid-content of milk, being .characterized by the moisture content in exce'ss of one per cent. (1%), containing palpable particles, I being emulsifiable with water to form a liquid'havinga natural milk-like odor and appearance, and substantially free from any burned .or boiled flavor due'to the presence of caramelized or altered milk-sugar, altered casein, or altered lact-albumin.

- 8. The product-resulting from the desiccation in 'vacuo of the solid content of milk, being characterized by a moisture content between one and one half and five per cent. and containing palpable particles capable of forming anaqueous emulsion having natural milk-like odor, appearance and souring and peptonizing properties, said product having a specific gravity considerably less than and consisting only'of the natural original ingredients of milk in an unaltered and readily emulsifiable condition.

9. The productjresulting from the desiccation in c acuo of the solid content of milk,

being characterized by a moisture content between two and four per cent. and containing palpable particles capable of forming an aqueous emulsion having natural milkike odor, appearance'and souring-and peptonizing properties, said product having a s ecific gravity considerably less than an consisting only of the natural original ingredients of milk in an unaltered and readily emulsifiable condition.

11. The product resulting from the desiccation in vacuo of the solid content of milk, being characterized by amoisture content between two and four per cent. and. containing palpable particles capable, of forming an aqueous emulsion having natural milklike odor,-appearance' and souring and peptonizing properties, said product having a specific gravity approximately and consisting only of the natural original ingredients of milk in an unaltered and rea 11y e mulsifiable condition.

' In witness whereof, I have hereunto set i my hand at the city of New York, this ninth day of June, 1911, j

\Vitnessesi L. E. JOHNSTON,

EVELAND. 

